The great promise of self-driving cars is that they will save innumerable lives by removing the most fallible and unpredictable element from vehicle traffic: the human.

But in San Francisco at least, fickle human behavior is taking a stand.

The next level of driverless cars: how to solve the problem of humans falling asleep

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Two of the six collisions involving autonomous vehicles in California so far this year involved humans colliding with self-driving cars, apparently on purpose, according to incident reports collected by the California department of motor vehicles.

On 10 January, a pedestrian in San Francisco’s Mission District ran across the street to confront a GM Cruise autonomous vehicle that was waiting for people to cross the road, according to an incident report filed by the car company. The pedestrian was “shouting”, the report states, and “struck the left side of the Cruise AV’s rear bumper and hatch with his entire body”.

No injuries occurred, but the car’s left tail light was damaged.

In a separate incident just a few blocks away on 28 January, a taxi driver in San Francisco got out of his car, approached a GM Cruise autonomous vehicle and “slapped the front passenger window, causing a scratch”.

The police were not called in either case.

The two human-on-robot assaults are not the first time San Franciscans have fought back – physically – against robots.

In December, the local SPCA animal shelter removed its 400lb Knightscope security robot from the streets around its building amid backlash from residents and the homeless population who complained the robot was harassing them. While most residents simply complained about the robot’s presence, one person reportedly “put a tarp over it, knocked it over and put barbecue sauce on all the sensors”.

And in April, a drunk man was arrested after he allegedly attacked and knocked over another Knightscope security robot in Mountain View, the Silicon Valley town that is home to Google.

“Not every innovation is all that great for society,” the San Francisco supervisor Norman Yee, who authored the legislation, said at the time. “If we don’t value our society, if we don’t value getting the chance to go to the store without being run over by a robot … what is happening?”

Have you ever attacked a robot? Or wanted to? We want to hear from you! Contact julia.wong@theguardian.com